WASHINGTON — President Barack Obama downplayed chances for an Iran nuclear deal in a closed-door meeting with Senate Democrats, participants said Wednesday, while asking them to withhold judgment until any deal is complete.

Obama also insisted that he won't sign a weak deal, a message that won praise from senators who joined the president for wine and appetizers in the White House State Dining Room Tuesday evening.

"He was urging that we wait to see the actual terms of an agreement if there is one, and to have confidence that he would not sign a deal he viewed as flawed," said Sen. Chris Coons, D-Del.

Coons added that Obama said it was uncertain whether the Iranians would go along with some of the tougher conditions, and that a deal is "at best a 50-50 proposition."

The session Tuesday evening was part fence-mending after a testy debate over trade that divided Obama from many in his party last month. It was also an opportunity for Obama and Democrats to reset their relationship in preparation for the legislative session ahead as well as the remainder of Obama's presidency.

A top focus was Iran, according to several lawmakers. Prospects are uncertain for the Obama administration to complete a deal, but if the accord isn't sent to Congress by Thursday, its month-long review period would be doubled to 60 days.

Obama has expended significant political capital on finalizing an agreement to keep Iran from going nuclear, prompting Republicans to accuse him of making too many concessions and even some Democrats to express deep ambivalence.

"He wanted to make it perfectly clear that he is in no rush to an agreement and that he will walk away from the table if there is no good deal to be reached and that there isn't a deal yet and so all of these reports about what is in a deal are premature," said Sen. Chris Murphy, D-Conn.

Participants said that after Obama's opening remarks, the reception with senators and Cabinet members turned into an unusually friendly and free-flowing question and answer session ranging from climate change, to politics, to the church shooting in Charleston, South Carolina, to the budget, to rare diseases, to health care in the wake of the Supreme Court decision upholding Obama's health care law.

As such it was a somewhat remarkable session for a president whose generally hands-off relationship with Congress has caused much fuming on Capitol Hill over the past six years. It was also notable that Obama's last formal meeting with congressional Democrats was when he paid an 11th hour visit to Capitol Hill last month to beg House Democrats to save his trade agenda, only to watch them vote it down in a stunning denial.

The trade bill was later revived by Republican leaders, leaving some hard feelings among Democrats.

"The president wanted to make sure that the trade debate had not left too many raw wounds among the Democratic family," said Sen. Tim Kaine, D-Va.

Democrats and the president also discussed standing firm on one looming issue: the annual spending bills which must be agreed to by Oct. 1 to keep the federal government running. Democrats are refusing to sign onto GOP-written bills, saying Republicans must sit down with them to negotiate on their demands for higher domestic spending levels, which so far Republicans have refused to do.

"The president was pretty clear about we need to sit down and negotiate, and the only way we can do that is stay united against the caps Republicans have put in their budget," said Sen. Ben Cardin, D-Md.